The present invention relates to a steering locking device which is able to prevent lock of a steering shaft due to failure or malfunction caused during running of a vehicle.
In a steering locking device installed in a vehicle such as a car, an engine can be started by inserting a key into a cylinder lock and then rotating this cylinder lock by the key from a LOCK position to a START position sequentially.
In a recent steering locking device, an electric current is supplied to a motor incorporated into the steering locking device via an electronic button or a radio wave, then a rotor cam is moved reciprocally by rotation of the motor from the LOCK position to the START position, and then a locking bolt is shifted simultaneously with switching of an ignition switch in the same manner as a key operation.
After the engine is started, the rotor cam is returned from the START position to the ON position. At that time, in the event that the rotor cam is driven by the motor, a timing to return the rotor cam from the START position to the ON position becomes more important.
As an improved timing to return the above-mentioned rotor cam, a steering locking controller driven by a motor has been known, as set forth in Patent Application Publication (KOKAI) 63-71458, for example.
As shown in FIG.5, in this steering locking controller, a push button 111 is provided to a front central portion of a housing 109 and a motor driving unit 105 is provided on the back side of the push button 111.
As shown in FIG.6, when a password number is input into a control station module 102 via a plurality of push button switches 101, a motor driving device 105 is controlled by a microcomputer 104 including a CPU.
A motor (not shown) is driven by action of the motor driving device 105 to thus rotate a rotor cam (not shown). At that time, an ignition switch 108 is switched to the LOCK position, the ACC position, the ON position, and the START position sequentially with the rotation of this rotor cam.
A sound generating circuit 106 may inform the driver of respective rotating positions by sound every switching of respective positions. When the rotor cam is positioned at the ON position or the START position, the sound generating circuit 106 may instruct the driver of the vehicle by sound so as to push the push button 111 provided to the steering locking device.
When the driver pulls in his or her finger from the push button 111 at the same time when the engine is started, this push button 111 can be automatically restored by a spring force of a spring. At that time, a position of a contact point of the rotor cam is inverted to the ON position of the ignition switch 108 together with the motor.
However, in the steering locking device in the prior art, the steering shaft (not shown) is locked by a driving force of the motor, the solenoid, etc. when the ignition switch 108 is positioned at the LOCK position.
For instance, normally the ignition switch 108 is at the ON position when the car is running, nevertheless there may be some cases where the password number indicating this ON position is changed to another password number indicating the LOCK position due to noise, or the like.
In other words, these is a possibility that the steering shaft is locked because of failure or malfunction by the noise, etc. caused during running of the vehicle and a serious accident will be caused consequently.